[N]either the food limit nor the beasts of prey are a very important check on the multiplication of organisms. The lion, for example, was never so numerous as to reach the limit of its food supply. Before the white man obtained a foothold in Africa vast herds of herbivores were to be seen in those districts where lions were most plentiful. … The chief bar to the increase in numbers of this species appears to be the teething troubles to which the whelps are liable. Now suppose that a mutation were to occur in the lion. Suppose that several members of a litter were all bright blue, and that these suffered from no teething troubles. They would probably all grow up, and although at some disadvantage as hunters on account of their conspicuous colouring, they would nevertheless probably increase at the expense of the normally coloured lions, because of the immunity of their offspring from death from teething troubles. Zoologists would then be at a loss to explain their bright colouring. We should have all manner of ingenious suggestions raised, namely, that in the moonlight these creatures were really not at all conspicuous, indeed that they were obliteratively coloured. In other words, a totally wrong explanation of their colouring would be given and accepted. It is our belief that many of the explanations put forward and accepted of the colouration of existing species are wide of the mark.


Let us, in conclusion, briefly summarise what we now know of the method in which new species are made. We have studied the various factors of evolution — variation and correlation, heredity, natural selection, sexual selection, and the other kinds of isolation. How do these combine to bring new species into being, and to establish the same? … Natural selection, although a most important factor in evolution, is not an indispensable one. Evolution is possible without natural selection. … Natural selection does not make new species. These make themselves, or, rather, originate in accordance with the laws of variation. … Variation brings into being mutants, which are incipient species, but variation cannot determine their survival. It is at this stage that natural selection steps in. … The Civil Service Commissioners do not make Indian civil servants: they merely determine which of a number of ready-made men shall become civil servants. Similarly, natural selection does not make new species, it simply decides which of a number of ready-made organisms shall survive and establish themselves as new species. Nor does natural selection always do as much as this; for it is not the only determinant of survival. Its position is sometimes comparable to that of the Medical Board which inspects and rejects the physically unfit of the candidates which have already been selected by some other authority.


Our aim in writing this book has been twofold. In the first place we have attempted to place before the general public in simple language a true statement of the present position of biological science. In the second place, we have endeavoured to furnish the scientific men of the day with food for reflection.

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A wonderful book. Many of the fallacies which the authors dismiss are still part of “popular science” books claiming to explain evolution.